| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.12 ( July 1985 ) Special Issue on Hot-and Cold-rolled Steel Sheets ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Manufacturing Methods and Properties of Hot-Dipped One-Side Galvannealed Steel Sheets by the Stop-Off Coating Technique Shigeru Kobayashi, Hideo Kohmura, Toshio Ichida, Toshio Irie, Katsunori Akiyoshi, Susumu Azuma |
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Synopsis : Manufacturing methods and properties of non-grinding hot-dipped one-side gvalvannealed steel strip are described. It is produced on the continuous galvanizing line which is equipped with a roll coater for stop-off coating by sodium silicate, sodium borate, magnesium oxide, titanium oxide and aluminum oxide, and a roll bender to remove the coating. (1) Above 800 the stop-off coating forms dense glass film which keeps one side of the strip surface from molten zinc and air atmosphere and is easily exfoliated from the strip using the roll bender after galvannealing. (2) Titanium oxide in needle-like crystals, recrystallized on the coating surface, prevents zinc sticking between 800 and 900. (3) Slightly absorbed zinc and magnesia on the bare side after removing the coating improve phosphate nucleation and corrosion resistance after painting. (4) The one-side galvannealed steel sheet using extra low carbon steel containing niobium shows extra deep drawability, having an elongation of 49% and ar value of 2.0. |
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